Interpretive Summary: Studies over the last couple of years have shown the USDA-ARS developed powered roll gin stand (PRGS) capable of improving ginning rate, turnout, and fiber quality relative to conventional saw-type gin stands. The prototype and initial field evaluation models, where the technology was validated, were Continental Eagle makes and models of gin stands. Consequently, field trials in commercial gins where the PRGS technology was installed on non-Continental Eagle equipment did not always show the levels of improvement previously reported, resulting in a theory that the technology did not work on any other makes and models of gin stands other than Continental Eagle makes and models. Investigation as to the differences between the models of gin stands for which the powered roll was working and those for which it had less than desirable results revealed the primary difference were the rib rail angle and location of the ginning point. Studies were performed on a retrofitted Lummus-116 gin stand at the USDA-ARS gin lab in Lubbock, TX, to evaluate the hypothesis that the rib rail angle and ginning point location were the reasons why the PRGS technology was not as effective on makes of gin stands other than those used to develop the technology. Results validated that the rib angle and ginning point were the problem. Findings from the studies revealed that the rib rail angle needed to be reduced by four degrees and the gin point increased by 0.5 inches from the rib angle and gin point settings previously used on all Lummus retrofits evaluated to this point. The findings demonstrate that the initial concept that all that was needed to implement the PRGS technology on an existing gin stand was to replace the front was in error: the rib rail angle and ginning point location need to be considered when retrofitting any existing gin stand with PRGS technology.

Technical Abstract:
Previous studies have shown the powered roll gin stand (PRGS) is capable of improving ginning rate, turnout, and fiber quality relative to a conventional gin stand; however, most of these studies used Continental Eagle gin stands, the gin stand used to develop the initial prototype and the one used in the initial field trials. Field experience in commercial gins where the PRGS technology was installed on non-Continental Eagle equipment did not always show the levels of improvement previously reported. Investigation as to the differences between the models of gin stands for which the powered roll was working and those for which it had less than desirable results revealed the primary difference were the rib rail angle and location of the ginning point. A study was conducted on a retrofitted Lummus-116 gin stand to evaluate the hypothesis that the rib rail angle and ginning point location were the reasons why the PRGS technology was not as effective on makes of gin stands other than those used to develop the technology. Results validated the hypothesis and indicated that the rib rail angle needed to be reduced by four degrees and the gin point increased by 12.7 mm from the initial settings on the Lummus-116. The findings demonstrate that the initial concept that all that was needed to implement the PRGS technology on an existing gin stand was to replace the front was in error: the rib rail angle and ginning point location need to be considered when retrofitting any existing gin stand with PRGS technology.